Grinding machine



Dec. 27, 1938. c, HERFURTH 2,142,028

GRINDING MACHINE Filed Sept. 7, 1937 4 Sheets-Sheet 2 1x5 (a l- 4 1 N VENTOR.

ATTORNEY.

C. HERFURTH GRINDING MACHINE Dec. 27, 1938.

Filed Sept. 7, 1957 4 Sheets-Sheet 3 INVENTOR 014p; ff /%"/P////?7// ATTORNEY.

4 Sheets-Sheet 4 @HNW C. HERFURTH GRINDING MACHINE Filed Sept. 7, 19:57

Dec. 27, 1938.

M nw Patented Dec. 27, 1938 PATENT OFFICE GRINDING Charles Hcrfurth, Cincinnati, Ohio, assignor to Cincinnati Grinders Incorporated, Cincinnati, Ohio, a corporation of Ohio Application September 7, 1937, Serial No. 162,622. i

19 Claims.

This invention relates to machine tools and more particularly to improvements in grinding machines.

One of the objects of this invention is to provide an improved automatic infeed cycle mechanism for grinding machines.

Another object of this invention is to so contrive an automatic hydraulic infeed cycle mechanism that it maybe push button controlled for starting purposes.

A furtherobject of this invention is to provide an automatic infeed cycle mechanism having variable means for predetermining the variable elements of the cycle such as the'total length of i5 stroke, the length of the rapid traverse approachmovement, the rate of the feeding movement and within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

Referring to the drawings in which like reference numerals indicate like or similar parts:

Figure 1 is a front elevation of a grinding mation.

Figure 2 is a detail sectional view showing the interlocking mechanism between the traversingmechanism and the infeeding mechanism, as

viewed on the line 2,-,- -,-2 of Figure 1.

Figure 3 is an end view of the valve block as viewed on the line 3-.-3 of Figure 1-.

Figure 4 is a section through the valve block as viewed on the line 4-4 of Figure 3.

Figure 5 is a section through the gearing shown in Figure 4 as viewed on the line 5-5 ofthat figure.

Figure 6 is a sectional view through the ma-' chine as viewed on the line 6-6 of Figure 1.

Figure 'I is an enlarged detail view through a rate control valve.

Figure 8 is a diagrammatic view of the hydraulic control circuit.

Referring to Figures 1 and 6 of the drawingsthe reference numeral ll indicates the bed of I chine embodying the principles of this inven a grinding machine in which is embodied the principles of this invention. The grinding wheel support H and the work support or work table 12 are mounted for relative traversing movement and for relative infeeding movement whereby 6 either traverse grinding or infeed grinding may be performed on the machine. For purposes of illustration the grinding wheel support II is fixed with the bed l0 and the table l2 executes the movements, it being guided'on ways I3 and l4 10 for traversing movement and these ways are formed on a saddle 15 which, in turn, is supported on ways It and I! as shown in. Figure 1 for moving the table l2 toward and from thev grinding wheel l8 which is rotatably mounted on 15 the support I I.

It will be understood that both of these movements could be imparted to the grinding wheel or either one of the movements imparted to the grinding wheel and the remaining moveso ment imparted to the work support without departing from the principles of this invention.

Any suitable form of known traversing mechanism may be provided for traversing the table I2 but for illustrative purposes a cylinder l9 hav- 2 ing' a contained piston 20, which is connected by a piston rod 2| to the table, is illustrated as constituting one suitable form, and it will be understood that a hydraulic control circuit which is not shown may be provided for governing operation of the table l2 and having a start and stop control lever which is indicated in Figure 2 by the referencenumeral 22.

During traverse grinding it is the usual practime to ieed'the work toward the grinding wheel 8!. at the end of each stroke of the table and a conventional pick feed mechanism for this purpose is illustrated in Figure 6. As shown in that figure, a screw 23 which is carried by the saddle l5 has a threaded engagement with a nut 26 40 which is fixed with the bed III. This screw has a gear 25' keyed to one end and connected by an idler 26 to a pinion 21 keyed to the reduced end of shaft 26. For micrometric manual adjustment the shaft 28 is' provided with a gear 23 46 which intermeshes with a pinion 36 which is. journaled in the housing 3| and formed integral with ashaft 32 upon the end of which is formed a gear 33. This gear intermeshes'with a pinion 34 integral with shaft 35 which is keyed to .the hand lever 36.v Byrotation of the hand lever the pinion 36 rotates the gear 33 and thereby through the interconnection of pinion 33 and gear 29 the pinion 21 may be rotated.

The lever 36 may be connected by 'the handle s 31 having a reduced end 38 which may be inserted in any one of a plurality of holes 39 formed in the pick feed wheel 49. An oscillatable lever 4| having a pivoted pick feed pawl 42 is provided for indexing the wheel 40 at the end of each stroke of the table inaccordance with conventional practice, whereby the work may be fed toward the grinding wheel at the end of each table stroke.

Due to the micrometric nature of this pick feed mechanism it is unsuitable for use in efiecting an infeeding cycle, and therefore, a separate mechanism has been provided which in no way interferes with the pick feeding mechanism nor with the power traversing mechanism for the table, with the exception that it is interlocked with such mechanism through the start and stop lever 22 shown in Figure 2, whereby power traversing and power infeeding cannot take place at the same time.

The actual movement between the saddle and grinding wheel is effected by a hydraulic motor comprising a cylinder 43 formed integral with the saddle and having a contained piston 44 which is directly secured to the end of the lead screw 23, a portion of the lead screw acting in this case as a piston rod. Since the screw 23 cannot move axially without rotation relative to the nut 24 the piston 44 becomes the stationary element and the cylinder 43 the moving element.

The introduction of fluid into the cylinder 43 is controlled by a servovalve mechanism comprising a servo-valve 45 having a plunger '46 which is continuously held against the end of a control lever 41 by means of a spring 48 mounted in one end of the valve housing. This valve has a pressure port 49, a pair of exhaust ports 50 and and a pair of motor ports 52 and 53 which are located between the pressure port, and the respective exhaust ports 50 and 51. The motor ports 52 and 53 are connected by channels 54 and 55, respectively, to opposite ends of the cylinder 43. The lever 41 is pivotally supported at 56 to the end of a reciprocable plunger 51 whereby,

.upon axial movement of the plunger the pivot 56 is moved through space. The end 58 of the lever 41 is connected to the screw 23 by interfitting in an annular groove 59 formed on the screw, as shown in Figures 6 and 8. It will now be apparent'that if the pivot point 56 is moved in a direction to permit the-spring 48 to shift the servovalve plunger 45 away from its center position that the pressure port 49 will be connected to the motor port 53 and fluid will be introduced into cylinder 43 in a manner to cause movement of the saddle away from the grind ng wheel; and since the servo-valve 45 and plunger 51 are carried by the saddle, the pivot point 56 will also be moved with the saddle and furthermore, since the end of lever 41 is fixed with the now immovable screw, a rotation of lever 41 in a clockwise direction about pivot 56 will-result, and the servovalve plunger 46 will be moved back against the compression of spring 48- to close the pressureport 48. Thus. the servo-valve plunger 46 is caused to follow up the movement of the saddle. Should the plunger 51 be moved relative to its housing 60, while the saddle is stationary, in a downwarddirection, as viewed in Figure 8. it will cause a clockwise rotation of lever 41, due to the end 58 being fixed, and thereby move the servo-' valve plunger 46 downward, connecting port 49 to motor port 52 and thus introducing pressure into the other end of cylinder 43.

This will cause the saddle to move toward the grinding wheel and also cause the pivot point 56 to move in the same direction but in so movin will cause a relative counterclockwise direction of rotation of lever 41 and permit the servo-valve plunger to come back to a central position under the pressure of spring 48 and close the pressure port 49. Thus, regardless of the direction of movement of the plunger 51 to open the servovalve, the resultant movement of the saddle will cause a follow-up movement to take place which will reposition the servo-valve plunger in a. central or stop position.

The housing 60 for the plunger 51 is in fact a rotatable sleeve which is journaled at 6| in the saddle 15, as shown in Figure 5, and held against axial movement by means of a flange formed on one end, and a gear 63 attached to the other end; A pin and slot connection is provided between the sleeve and the plunger whereby, upon rotation of the sleeve, a positive axial movement may be imparted to the plunger. As shown in Figure 8, the groove 64 is spirally cut in the sleeve and a pin 65 fixed with the plunger with its free end entering the groove. Since the plunger isheld against rotation it will be apparent that rotation of the sleeve will cause lateral movement of the pin and thereby axial movement of the plunger 51.

The sleeve during an automatic cycle is power rotated and the control circuit shown in Figure 8 controls this power actuation in such a manner as to cause the saddle to execute an automatic cycle including the following steps: rapid traverse approach to grinding position, infeed, dwell to permit the grinding wheel to clean up the work and finish it to desired size, rapid return and stop.

The power actuator comprises a hydraulic motor in the form of a cylinder 66 and contained piston 61. As shown in Figure 4, the piston rod 68 projects beyond both ends of the cylinder and on one end is provided with one set of rack teeth 69 intermeshing with an idler gear 10, and a second set of rack teeth 11 which intermesh with gear 12. The idler gear meshes with gear 63 previously mentioned as attached to the end of the rotatable sleeve 60. The idler gear 10 has an arcuate slot formed therein into which extends a fixed pin 14 which acts as a means to limit the maximum stroke .of the piston 61 in either direction.

The hydraulic circuit shown in Figure 8 serves to automatically control the rate and direction of movement-of the piston 61 and to that end. the circuit is provided with a reversing valve which determines the direction of movement of the piston 61; a pilot valve 16 which causes power shifting of the reversing valve; a rate valve 11 which determines the rate of the feeding movement; a tarry valve 18 which determines the length of pause of the grinding wheel while finishing the work to size; a rapid traverse control valve 19 which determines the-length of the rapid traverse approach movement; and a start and stop valve 80. This circuit is supplied with fluid pressure from a pump 8| which has an intake 82 through which fluid is withdrawn from a reservoir 83, and a delivery pipe 84, which has a branch connection to a relief valve 85. The channel 84 not only supplies fluid pressure to the pressure port 49 of the servo-control valve, but also to ports 86 and 81 of the pilot valve 16, and port 88 of the reverse valve 15.

The plunger 89 of the reversing valve 15 is shown in a position for causing movement of the work toward the grinding wheel and the piston 61 is shown in a starting position ready to start I this movement. In this position of the parts the fluid from pressure port 86 will flow through the cannelure 90 of plunger 69 to port 9I which is connected by channel 92 to port 93 of the start and stop control valve 80. This valve has a plunger 94 to the end of which is attached a large push button 95. In the stop position this plunger is to the left of that in which it is shown and in its left position a spool 96 closes port 91, which is connected by channel 98 to port 99 located in the left hand end of cylinder 66.

It will now be apparent that if the operator presses the push button 95 the plunger 94 will move toward the right and into the position in which it is shown in Figure 8. This will connect the port 93, which is already connected to the pump by the reversing valve, to port 91 and thereby to the left end of cylinder 66. The fluid from the other end of the cylinder will return to reservoir through port I00, channel IOI, port I02, cannelure I03, port I04, channel I05 to port I06 of the rate valve 11. This valve, howeyer, forms a high resistance to flow in this direction and therefore a check valve I01 in channel I05 will open, permitting the fluid to flow to port I08 of the rapid traverse control valve 19. This valve has a plunger I09 which is threaded at IIO into a yoke III which is attached at I I2 to the end of piston rod 68, whereby the plunger I09 moves simultaneously with the piston 66. The plunger I09 has an annular groove II3 which serves to interconnect port I08 with port II4. Thus, the fluid will continue to flow through port H4 and channel .I I5 to port II6 of the reversing valve 15. The plunger 89 of the reversing valve is in a position such that the cannelure II1 thereof interconnects port 6 to port H0 which is connected by channel II9 to reservoir. Since the check valve I01 is a low resistance check valve, it will be apparent that the fluid escaping from the right hand end of cylinder 66 has a relatively free passage to reservoir, thus offering very little resistance to the movement of piston 61 whereby the same may move at a rapid traverse rate.

The length of the rapid traverse positioning movement will vary, of course, with the diameter of the work and therefore by providing the threaded engagement of the plunger I09 in the yoke III the position of the plunger I09 with respect to the piston 66 may be varied so that the time of closing of port II 4 by the spool I20 may be varied. This is because the closing of. port I I 4 will stop the rapid traverse movement in that it will close the open passage to reservoir and cause additional returning oil to be forced through the rate valve 11. In order that the position of plunger I09 may be preset, the end of the plunger is provided with a manually operable knob I2I which has an integral sleeve I22 telescoping the nut portion I23 of the yoke and the surface of this may be graduated in conjunction with suitable graduations formed on the tapered end of the sleeve I22 in the nature of a micrometer to predetermine the length of the rapid traverse movement. a

The rate valve 11 has a plunger I24 .which is threaded at I25 in the end of the housing and provided with a manually operable handle I26, whereby longitudinal position of the plunger and the housing may be varied. This is for the purpose of varying the position of V notches I2-1 formed on the valve spool I26 with respect to the port I06 to thereby change the resistance of this port to the escape of fluid to reservoir and thereby the rate of the feeding movement. The fluid passing through this resistance accumulates in annular groove I29 which is in communication with port I30 whereby fluid will continue through channel I3I to port II6 of the reversing valve and thereby to reservoir. It will now be noted that the rapid traverse control valve and the rate valve are connected in parallel between the port I 04 of the start-stop valve 80 and the port II6 of the reversing valve whereby the fluid flows part of the time through the low resistance circuit including the rapid traverse valve and then when this valve closes, the fluid goes through the high resistance circuit including the rate valve whereby the rapid traverse movement is slowed down to a feed rate.

The feeding movement continues until another portion I32 of the yoke III pulls the plunger I33 of the pilot valve 16 toward the right" as viewed in Figure 8. The plunger I33 has a reduced portion I34 which passes through-a. hole I35 in the yoke whereby the yoke may move with respect to the plunger until it hits an adjustable dog I36 secured to the plunger. By changing the position of this dog it will be apparent that the point of reversal may bechanged, or in other words, the size of the work determined.

When the plunger I33 is shifted to the right it disconnects the pressure port 81 from port.

I31 which is connected by channel I38 to the left end of reversing valve housing 15. In addition, it connects pressure port 86 to port I39, which, in turn, is connected by channel I40 to ports I41 and I42 of the tarry valve 18, and it will be noted that the central spool I43 of the plunger I33 is larger in diameter than the end spools whereby after the port 66 is cracked and pressure fluid flows into the annular groove I44, the pressure differential created by the difference in end area of the opposing spools will complete the shifting movement in the manner of a load and fire mechanism. Completion of this shifting movement will result in port I31 being connected to reservoir port I45 whereby the left end of the reversing valve housing 15 is open to reservoir so that upon admission of pressure to port I46 the plunger 89 will be shifted to the left. The port I46 is connected by channel. I41 to port I48 of the tarry valve. This valve is constructed exactly the same as the rate valve whereby the port I is connected through a high resistance to port I48 so that fluid will.

flow through there at a slow rate. The resistance ofthe tarry valve will, of course, be higher thanthe rate valve in order that .an appreciable tme will pass before suflicient fluid pressure is built up in the right hand end of the reversing valve 'to cause shifting of its plunger.

In spite of the shifting of the pilot valve plunger, no change has been made in the operating circuit and the piston 61 still continues to move. A positive stop has been provided to function at this point so that even though the piston 61 continues tomove it will merely cause an increase in the pressure in-cylinder 43 without causing further movement of the saddle. This stop positively determines the size of the work and is adjustable independently of the operating mechanism for varying. the size of the work. This positive stop comprises a thrust bearing I49 which is mounted between the cylinder head I50 of the cylinder 43 and a loose washer II which is supported on a reduced portion I52 of the screw, 23 for movement relative thereto. The washer is adapted to fit in a countersink I53 formed in the end of the hub of gear 25, which gear is fixed against axial movement with respect to the saddle I5. The screw has an enlarged splined portion I54 by means of which the gear 25 is connected for rotation of the screw while permitting relative axial movement therebetween. The splined portion I54 forms a shoulder I55 against which the washer I5I is adapted to abut during inward movement of the saddle relative to the screw, thus forming a positive stop to the inward movement of the saddle.

If it is desired to change the size of the work being ground, the screw 23 may be rotated through the gear 25 by means of the mechanism shown in Figure 6 and since the screw is threaded in the fixed nut 24 it will move axially and thereby change the position of the shoulder I55 in space and thereby change the stop position of the saddle.

It will now be evident that even although the reversing valve is not immediately shifted by the tripping of the pilot valve and that the piston 61 still continues to move a small amount, the size of the work has been accurately determined and it is merely necessary to allow sufficient time for the grinding wheel to spark out before the reversing valve is tired. The amount of this time is determined by the setting of the tarry valve and eventually it will effect shifting of the reversing valve into its left hand position.

When this has been accomplished, the port 88 will be connected to port I I 6 and fluid pressure will flow to the port I30 of the feed rate control valve 11. Fluid pressure flowing in this direction will pass into the annular groove I29 and through diametrical passages I56 into an axial bore I51. One end of this bore is closed .by a spring pressed ball I58 which acts as a check valve. .Pressure coming in this direction will easily open this check valve and the fluid pressure will flow past theball and out through radial holes I59 into annular groove I60 and thereby to port I6I. This port is connected by channel I05 to port I04 of the start and stop valve whereby the fluid will continue through annular groove I03, port I02 and channel IOI to port I located in the right hand end of cylinder 66. Since the check valve in the rate control valve is a low pressure check valve, it will be apparent that there is very little resistance to the flow of fluid and therefore the piston 61 will move back at a rapid rate. The return fluid from the other end of the cylinder will return to reservoir through port 99 located in the left end of the cylinder 66, interconnected ports 91 and93 of the starting valve 80, channel 92, interconnected ports 9I and I62 of the reversing valve to the return channel I63.

Near the end of the rapid return movement of piston 61, the pilot valve I33 will be shifted into the position in which it is shown in Figure 8. This will reconnect pressure port 81 to port I31 whereby the fluid will flow through channel I38 to annular groove I64 in which is formed two sets of radial ports I65 and I66. At the moment,

.port I66 is connected to port I61, due to the fact that the plunger 89 is in its left hand position. This will cause the pressure fluid to flow through channel I68 and past the low pressure check valve I69 to channel I10 which leads to the right hand end of the start and stop valve 80. The end of this valve is also connected by a high fluid, resistance coil I1I to return channel I12. The result of this is that the shot of high pressure fluid into channel I10 will shift the valve plunger 94 into a stop position which will disconnect ports 93- and 91. At the same time, fluid will be flowing through port I65 into the left'hand of valve 15 and immediately afterward will shift the plunger '89 to the right. The delay in movement will be caused by forcing the fluidin the' right hand end of the cylinder through channel I41 and the tarry valve 18. This valve is constructed the same asthe valve shown in Figure 7 with the exception that the spring which holds the check ball is made stronger so that this valve will not open before the check valve I69 opens. Thus, it is possible to cause the stop and start valve to move to a stop position before the reversing valve is shifted.

The returning fluid from port I42 of the tarry valve 18 will pass through channel I40, interconnected ports I39 and I13 to return channel I63. Thus, the circuit is reconditioned for another cycle.

It will be noted that when the start and stop valve plunger 94 is in its stop position that ports 91 and I02 will be interconnected and ,thus condition the circuit so that the piston 61 may be moved manually without resistance to the fluid in either end of cylinder 66 because upon movement of piston 61 the fluid in one end of the cylinder will merely flow to the other end.

The mechanism for manually moving the servovalve to cause in and. out movement of the saddle is shown in Figure and comprises'a manually operable lever I14 which is keyed at I15 to a clutch member I16. This clutch member is normally held out of engagement with a clutch member I11 which is pinned to the shaft I18 to which is fixed the gear 12. This is effected by a spring I19 which is interposed between the two clutch members, and to prevent inadvertent engagement of the clutches a spring pressed plunger I80 is reciprocably mounted in a boss I8I formed integrally with the handle I14, and the end of the plunger has 'a reduced portion I82 which is adapted to engage a notch formed in the end of shaft I18. When it is desired to effect manual operation, the operator pulls out the plunger I80 by means of the knob I83 formed on the end thereof and pushes inwardly on the handle to effect engagement of the clutch members. These parts have to be held together during manual operation and when they are released they will return to the position shown in Figure 5, and thereby insure against inadvertent" operation during power actuation of the device.

When it becomes necessary to true the wheel the trueing tool is mounted on the saddle and the saddle is moved inward to the limit of its stroke and held in that position during reciprocation of the table. This is accomplished by providing a pivoted latch member I84 which swings about a pin I85 as shown in Figure 3 and the end of the latch member has a slot I86 cut in one side thereof so that it may fit down over the rod I34. During the automatic operation of the cycle, as previously explained, the latch is in the position shown in Figure 3. Upon rotation of this latch in a counterclockwise direction, as viewed in Figure 3, it will be withdrawn from its position between the yoke III and the trip dog I36. This means that the piston 61 can move to the end of its stroke asdetermined by the stop pin 14 without the yoke III engaging the trip dog I36. Thus, the saddle will move in and be held in that position by hydraulic pressure. After the trueing operation has been completed the opera- 1 er IBI.

tor manually shifts the pilot valve by grasping the dog I36, which, in turn, will eventually cause shifting of the reversing valve and return movement of the parts to a starting position. In order to insure that the infeeding cycle is not thrown intooperation while the table is traversing, an interlock has been provided between the starting member 22 for the reciprocating cycle and the infeeding mechanism. This interlock is shown in Figure 2 and comprises a lever I8'I which is centrally pivoted at I88 and connected at one end by a pin I89 to a starting lever 22 and at the other end by a pin I90 to an interlock plung- This plunger has a notch I92 formed therein for receiving an interlocking pin I93. This pin is adapted to engage a notch I94 formed in the periphery of gear 63 secured to the end of sleeve 60. It will be noted that the pin I93 is of such length that it will prevent simultaneous actuation of both mechanisms.

There has thus been provided an improved automatic infeed mechanism for a grinding machine, while although hydraulic in nature, has a push button type of starter, and which includes means for adjusting all of the variable elements involved in such a cycle, and which will automatically stop after a cycle has been completed.

What is claimed is:

1. In a grinding machine having a work support and a. grinding wheel support and a cooperating screw, and a nut mounted on the respective supports, a piston integral with said screw, a cylinder enclosing said piston and attached to one of said supports, a servo-control valve having fluid connections to said cylinder, a power operable member for actuating said servo-valve, and a one-cycle control circuit for said power operable member including a starting valve for coupling pressure to said member, and means operable at the end of the cycle for repositioning said valve in a stop position.

2. In a grinding machine having a grinding wheel and a work support, the combination of an infeeding mechanism for efiecting relative movement between said supports including a servomotor control mechanism, a fluid operable piston operatively connected for control of said servomotor mechanism, a one-cyclefluid control circuit for said piston including a start and stop valve, manually operable means for shifting said valve to a running position, and fluid operable means automatically effective at the end of a cycle for repositioning said valve in a stop position.

3. In a grinding machine having a. grinding wheel and a work support, the combination of a hydraulic servo-motor including a control valve for feeding one of said supports relative to the other, a fluid operable piston, motion transmitting means coupling said piston for movement of said servo-valve whereby the rate of movement of said piston will determine the rate of movement between said supports, and a hydraulic control circuit, for said piston including means for causing a rapid movement and then a feeding movement, and means for automatically changing the rate from one to the other.

4. In a grinding machine having a grinding wheel and a work support, the combination of means for effecting relative movement between the supports to effect a grinding operation including a flrst fluid operable motor, a rate and direction control valve therefor, a second fluid operable motor for actuating said valve, and a fluid control circuit for said second motor including means for automatically changing the unidirectional rate of movement thereof, and subsequently operable means for changing the direction of movement thereof.

5. In a grinding machine having a grinding wheel and a work support, the combination of an automatic infeeding mechanism therefor including a hydraulic motor, a servo-control valve mech anism, a fluid operable motor for actuating said servo-valve, a fluid control circuit for said lastnamed motor including a feed rate control valve and a rapid traverse control valve connected in parallel in said circuit, means to connect said rapid traverse valve for movement by said fluid operable motor, said means including an adjustable connection for varying the time of closing of said rapid traverse valve and thereby varying the length of the rapid traverse movement.

6. In a grinding machine having a grinding wheel support and a work support, the combination of transmission means for eflecting an automatic cycle of relative movement between said supports including rapid traverse advance, feed and rapid return, comprising a servo-motor and control valve, a fluid operable piston for moving said control valve, an operating circuit for said piston including a reversing valve, a pilot control valve for said reversing valve, a rapid traverse control valve, and a feed rate control valve connected in parallel between said reversing valve and said piston, means positively connecting said rapid traverse valve for movement with the piston, a lost motion connection between the piston and pilot valve'whereby during movement of the piston in one direction the rapid traverse rate may be changed to a feed rate, and the pilot valve may be shifted to change the direction of said movement.

7. In a machine tool having a work support and a tool support, the combination of power operable means for effecting relative movement between the supports including a reverser, fluid operable means forshifting said reverser including a pilot valve, a control member means for moving said member in proportion to the rate of movement between said supports, a lost motion connection between said member and the pilot valve for tripping same, and means-to disconnect the member and valve to prevent tripping of the pilot valve.

8. In a machine tool having a pair of relatively movable supports and power operable means for effecting a limited movement therebetween, the combination of a fluid operable member for con trolling the rate and direction of said movement, said member having positive means for limiting its movement in each direction, a control valve effective to change the direction of movement of said member, a lost motion connection between said member and the control valve for effecting tripping of the latter, and means to enlarge said lost motion whereby the member will reach the end of its stroke without tripping said control valve.

9. In a machine tool having a pair of relatively movable supports and fluid operable control means for effecting said relative movement, the combination of a hydraulic control circuit including a reversing control valve and a stop control valve,- fluid operable means for shifting said valves, individual check valves through which fluid must flow to cause shifting of the respective control valves,.one of said check valves being set to a higher resistance thanthe other whereby upon application of fluid pressure to the check 7 said motor including a reciprocable plunger, 9.

rotatable member enclosing the plunger, one of said parts havinga spiral slot therein and the other a pin engaged in the slot whereby rotation of the member will efiect translation of the plunger, and an auxiliary hydraulic motor for eflecting rotation of themember.

11. In a machine tool having a work support and a tool support, power operable means for efiecting relative movement between the supports including a hydraulic motor, a servo-control for said motor including a reciprocable plunger, a rotatable member enclosing the plunger, one of said parts having a spiral slot therein and the other a pin engaged in the slot whereby rotation of the member will effect translation of the plunger, an auxiliary hydraulic motor for effecting rotation of the member, and means for determining the rate and direction of operation of said second hydraulic motor.

12. In a machine tool having a work support and a tool support, power operable means for effecting relative movement between the supports including a hydraulic motor, a servo-control for said motor including a reciprocable plunger, a rotatable member enclosing the plunger, one of said parts having a spiral slot therein and the other a pin engaged in the slot whereby rotation of the member-will eiIect translation of the plunger, an auxiliary hydraulic motor for efiecting rotation of the member, and means for determining the rate and direction of operation of said second hydraulic motor, said means including a pilot' control valve and operative connections between said second hydraulic motor and said pilot valve for actuation o the valve by the motor.

13. In a' machine tool having a work support and a tool support, power operable means for efiecting relative movement between the supports including a hydraulic motona servo-control for said motor including a reciprocable plunger, a rotatable member enclosing the plunger, one of said parts having a spiral slot therein andthe other a pin engaged in the slot whereby rotation of the member will effect translation of the plunger, an auxiliary hydraulic motor for effecting rotation of the member, means for determining the rate and direction of operation of said second hydraulic motor, said means including a pilot control valve and operative connections between said second hydraulic motor and said pilot valve for actuation of the valve by the motor, andv adjustable means for varying the phase reaction of said motor on the valve.

14. In a machine tool having a work support and a tool support, power operable means for effecting relative movement between the supports including aiirst hydraulic motor, .a servomotor valve mechanism for controlling the feeding movement of said hydraulic motor; a second hydraulic motor for operating said servo-motor mechanism, and means for controlling the rate of actuation of said second motor including an adjustable feed rate determining valve, a rapid traverse selector valve, and operative connections between the second hydraulic motor and said lastmentioned valve for controlling efiective positioning of said valve. 1

15. In a machine tool having a work support and a tool support, power operable means for eifecting relative movement between the supports including a first hydraulic motor, a servo-motor valve mechanism for controlling the feeding mbvement of said hydraulic motor, a second hydraulic motor for operating said servo-motor mechanism, and means for controlling the rate of actuation of said second motor including an adjustable feed rate determining valve, 9. rapid traverse selector valve, operative connections between the second hydraulic motor and said lastmentioned valve for controlling efiective positioning of said valve, and means for varying said connections to change the phase relationship between said motor and valve whereby the extent of rapid traverse movement of the motor may be variably determined.

16. In a machine tool having a work support and a tool support, power operable means for effecting relative movement between the supports including a first hydraulic motor, a servomotor valve mechanism for controlling the feeding movement of said hydraulic motor, a second hydraulic motor for operating said servo-motor mechanism, and means for controlling the rate of actuation of said second motor including an adjustable feed rate determining valve, a rapid traverse selector valve, operative connections between the second hydraulic motor and said lastmentioned valve for controlling efiective positioning of said valve, and a hydraulic actuating circuit interconnecting said second hydraulic motor and said valves, said circuit including a bypass conduitwhereby the same may be selectively eiIective on the motor by way of or .exelusive of the rate control valve.

1'7. In a machine tool having a work support and a tool support, power operable means for effecting relative movement between the supports including a first hydraulic motor, a servomotor valve mechanism for controlling the feeding movement of said hydraulic motor, a second hydraulic motor for operating said servo-motor mechanism, and means for controlling the rate of actuation of said second motor including an adjustable feed rate determining valve, a rapid traverse selector valve, operative connections between the second hydraulic motor and said last-mentioned valve for controlling efiective positioning of said valve, a hydraulic actuating circuit interconnecting said second hydraulic motor I and said valves, said circuit including a by-pass conduit whereby the same may be selectively effective on the motor by way of or exclusive of the rate control valve, means for reversing the operative eflect of the hydraulic circuit as respects the motor, and a pilot circuit including a pilot valve intermittently actuabl by said second hydraulic motor for determining the eifective position of said reversing means.

18. In a machine tool having a work support and a tool support, power operable means for effecting relative movement between the supports including a first hydraulic motor, a servo-motor valve mechanism for controlling the feeding movement of said hydraulic motor, a second hydraulic motor for operating said servo-motor mechanism, and means for controlling the rate of actuation, of said second motor including an adjustable feed rate determining valve, a rapid traverse selector valve, operative connections between the second hydraulic motor and said lastmentioned valve for controlling eflfeetive positioning of said valve, 9. hydraulic/actuating circuit interconnecting said second hydraulic motor and said valves, said circuit including a bypass conduit whereby the same may be selectively efiective on the motor by way of or exclusive of the rate control valve, means for reversing the operative eflfect of the hydraulic circuit as respects the motor, and a pilot circuit including a pilot valve intermittently actuable by said second hydraulic motor for determining the effective position of said reversing means, said pilot circuit including a serially arranged tarry mechanism for eiifecting a delayed reaction of the pilot valve on the reversing valve.

19. In a machine tool having a work support and a tool support, power operable means for eiiecting relative movement between the supports including a first hydraulic motor, a servomotor valve mechanism for controlling the feeding movement of said hydraulic motor, a second hydraulic motor for operating said servo-motor mechanism, and means for controlling the rate of actuation of said second motor including an adjustable feed rate determining valve, a rapid traverse selector valve, operative connections between the second hydraulic motor and said lastmentioned valve for controlling eilective positioning of said valve, a hydraulic actuating circuit interconnecting said second hydraulic motor and said valvs, said circuit including a by-pass conduit whereby the same may be selectively eflective' on the motor by way of or exclusive of the rate control valve, means for reversing the operative efl'ect oi the hydraulic circuit as respects the motor, and a pilot circuit including a pilot valve intermittently actuable by said second hydraulic motor for determining the effective position of said reversing means, said pilot circuit including a serially arranged tarry mechanism for eflfecting a delayed reaction of the pilot valve on the reversing valve, and means for positively limiting the extent of support movement eflected by the first motor whereby overrun in relative movement of the supports under actuation of the first motor is prevented during the delay effected by the tarry mechanism.

CHARLES HIRFURTH. 

